Manufacture of metal carbonyls



Patented Apr. 9, 1935 UNITED SETATES PATENT OFFICE MANUFACTURED! METAL oAnBoNYLs Leo Schlecht," Iludwigshafen on-the-Rhine, and? V Emil Keunecke, Oppau, Germany, assignors to,

I. G. Farbenindustrie Aktiengesellschaft,

Frankfort-on the-Main, Germany No Drawing Application November '14, 1932, Serial No. 642,601.: In Germany September 17,

" carbonyls are converted into the metallic state,

' The process according to the present invention,

is based upon the surprising discovery that the gases and vapors formed during conversion of the initial material, by treatment with carbon monoxide, into the metallic state, such as carbon oxy-sulphide, hydrogen sulphide or carbon disulphide, do not interfere with the interaction of the metal or metals with'the'carbon monoxide for the formation of the metal carbonyl or car- 'bonyls.

The process which we have developed out of this discovery consists, as has been set forth in our application for patent Ser. No. 387,791, filed August 22nd, l929,- of which 'this application is a, continuation-in-part, in acting on an initial material of the aforesaid kind with carbon monoxide or a gas containing carbon monoxide under conditions, more particularly as regards the pressure and temperature and also the speed of the gas current, under which the formation of metal carbonyl takes place from initial material in the metallic state. Under such conditions the conversion of the initial material iinto the metallic state and the formation ofthe metal'carbonyl or carbonyls proceed simultaneously in a satisfactory mannerand at a sufiiciently' high speed, so that, instead of the old three-stage process, initial materials of the aforesaid kind can now be converted into metal c'arbonyls in only one stage, metal carbonyl being formed from the very start of the treatment. 7 r

We shall now proceed 'to explain more in detail theconditions under which the process according to the present inventionis carried out.

, a Claims. (01. 2s-203) Generally speaking, the pressure must be the higher, the higher the temperature. In this connection it must be borne in mind, that an equilibrium is set u in the gas in that on the one'hand metal and carbon monoxide react'with each other with the formation of carbonyLand on the other hand the carbonyl tends to decompose to metal and carbon monoxide, in accordance with the formula Me+nCO-- Me(CO)n H wherein Me is the metal capable of forminga metal carbonyl. Depending on the temperature and pressure, the one or the other of these re! actions will predominate and thus the yield in carbonyl will be influenced. Regard must also be had to the equilibrium lowing formula V In view of the aforesaid equilibria, attention must be given not only to the temperature and pressure, but also to thespeed of the .gas currentand, in case'fa gas containing carbon monoxide is used, such as a mixture of carbon mom oxide with nitrogen, hydrogen, carbon dioxide or methane, to the; composition of the gas. "All these influences are controlled by the law of mass action and are therefore readily determinable. It may be pointed out, however, that the speed of the gas current should usually be so high that the gaseous by-products of the reduction and also the metal carbonylfor'med are carried away by the gas current. The temperature and pressure conditions, moreover, vary according to the nature of the metal, which is to be converted into expressed by the folthe carbonyl: Such mutual interdependency of thetemperature and pressure conditions is .well known in the art from the production of metal carbonyls from metallic initial materials. Generally speaking the temperature and pressure should be of the same order in the process accordingxto the present invention as would be used in case the initial material were present in the metallic state. .It'is preferable to work at temperatures at which the carbon monoxide or the gases containing the same convert the metal compounds with a sumcient velocity into the metallic state, but the temperature must not be so high that the decomposition of the carbon monoxide becomes troublesome. By employing the carbon monoxide under pressure the permis sible temperature is raised in. consequence of the favorable state of the equilibrium of the reaction between the metals and the carbon monoxide,

20 atmospheres and more aresuitable forlthe.

process in accordance with thepresent invention.

The mutual interdependency of the tempera,- ture and pressure conditions will now be explained further by reference to some specific examples, to which, however, the invention is not restricted. t L:- u Example 1v Nickel sulphide precipitated by means of ammonium sulphide from a nickel salt solution is treated with streaming carbon monoxide under a pressure of 200'atmospheres and at 200 C. In thecourse of 2 hours 90 per cent of the nickel is converted into nickel carbonyl.

The carbon oxysulphide formed as a by-prodnot can be recovered as such or it may bedestroyed for example by means of alkaline agents whereby carbon monoxide is regenerated. The spent alkaline "agents may then be further treated for the production" of elementary sulphur or they may be treated for the production ofhydrogen sulphide which can then be used for precipitating metals 'from the solutions 010-,

tained "in the leaching of ores. The sulphides obtained maythen advantageously be used for the production;- pi metal carbonyls. At 200 C. and at a pressureof 200 atmospheres practically exclusively nickel sulphide is converted into nickel carbonyl by carbon monoxide. Under the said conditionsthe sulphides of other carbonylforming metals react only very diflicultlywith carbon monoxide. For the conversion. of these sulphides higher temperatures or higher pressures or bo'th must beused. In this way not only separation of the carbonyl-forming metals from the metals not capable of forming carbonyls is effected, but also the carbonyl-forming metals are separated from each other and especially the nickel is separated from iron andcobalt. Since the hydrogen sulphide can be easily regenerated in this manner of working and can be used again forthe precipitation, the process is very suitable for the :treatment of large amounts of leaching solutions and especially such as are so low in metals thattheir treatment was not'economical hitherto.

' Erample 2 I Precipitated iron sulphide is acted upon with,

acurrent of carbon monoxide at between'200 and 300 C. and under a pressure'of 1000 atmospheres. From 70 to 80 per cent of the iron present is converted into iron carbonyl. 1

' and 300 C. and under a pressure of at least 300 atmospheres for the production of iron carbonyl. It will be seen from the foregoing that the process according to the present invention is carried out under the same conditions under which the treatment with carbon monoxide would be effected if the metal or metals capable of forming metal carbonyls were initially present in the metallic state. The same is true with regard to the apparatus which are suitable for carrying out the process according to the present invention.

In case several metal carbonyls are formed simultaneously, they may be separated from each otherin any suitable manner, as for example by the methods of fractionation described and claimed in the copending application for patent, Ser. No. 637,200, filed October 10th, 1932, by Carl Muller and ourselves. 1 p

In the case of-initial materials containing two ormoremetals capable of forming metalcarbonyls, it maybe advantageous first to convert mainly one metal sulphide intothe corresponding metal carbonyl by the process according to the present invention, and then to subject the material under treatment to the old three-stage process by roasting, reduction and subsequent treatment with carbon monoxide for the recovery of the remaining metal or metals capable offorming a metal carbonyl" This method of working is illustrated byfExampleB given above.

When working with streaming carbon monoxide and when employing the excess of gas in a circular course, it is advantageous to remove from the gas undercirculation, either wholly or partly, the by-products formedby the conversion of the initialmaterials into the metallic state, such as carbon oxysulphide, carbon disulphide or hydrogen sulphide, and other impurities; for example, carbon oxysulphide may be removed when working under elevated pressure, by scrubbing the gas with aqueous or alcoholic caustic alkali solutions under pressure, after the metal carbonyl has been separated from the gas.

' The process according to the present invention is applicable to the treatment not only of metal sulphide or materials containing the same, but also of such compounds or mixtures of compounds as are-capable of being converted, under the conditions of the treatment with carbon monoxide, into the metal sulphides; as examples of such compounds or mixtures of compounds may be mentioned moist mixtures of alkali metal sulphides with metal sulphates or metal chlorides or other metal salts. .Suitable initial materials of the said kind are for example sulphidic ores or metallurgical intermediate or waste products such as those resulting from precipitation processes. All such initial materials are to be regarded as equivalents for the purposes of the present invention and aretherefore comprised in the followingclaims by the term material comprising a sulphidic compound. I What we claim is:- V filgThe. process of producing metal carbonyls which comprises acting with carbon monoxide on a material comprising a sulphidic compound of at least one metal capable of forming a metal carbonyl, under conditions of temperature and pressure, under which formation of a metal carbonyl would take place if the metal of said sulphidic compound were present in the metallic state.

2. The process of-tproducing metal carbonyls which comprises acting with carbon monoxide on a material comprising a sulphidic compound of at least one metal capable of forming a metal carbonyl at between about 150 and about 450 C. and under a pressure of atleast 20 atmospheres.

3. The process of producing nickel carbonyl which comprises acting with carbon monoxide on a material comprising a sulphidic compound of nickel at between about 150 and about 450 C. and under a pressure of at least 20 atmospheres.

4. The process of producing nickel carbonyl which comprises acting with carbon monoxide on a material comprising a sulphidic compound of nickel at between 150 and 275 C. and under a pressure of at least 50 atmospheres.

5. The process of producing nickel carbonyl nickel at 200 C. and under a pressure of 200 atmospheres. v

6. The process of producing iron carbonyl whichcomprises acting with carbon monoxide on a material comprising a sulphidic compound of iron at between about 150 and about 450 C. and under a pressure of at least 20 atmospheres.

7. The process of producing iron carbonyl which comprises acting with carbon monoxide on a material comprising a sulphidic compound of iron at between 220 and 300 C; and under a pressure of at least 300 atmospheres.

8. The process of producing iron carbonyl which comprises acting with carbon monoxideon a material comprising a sulphidiccompound of iron at between 220 and 300 C and under a pressure of 1000 atmospheres.

- LEO SCHLECHT.

EMIL 'KEUNECKE. 

